We are investigating the mechanisms whereby steroid and polypeptide hormones stimulate growth and specific protein synthesis in human breast cancer both in tissue culture model systems we have established and in clinical settings. A. We are studying the prevalency and clinical correlates of specific steroid receptors for estrogen, androgen, glucocorticoid and progesterone in human breast cancer, lymphomatous diseases, melanoma, colon carcinoma, ovarian cancer and male breast cancer. B. Assays for specific gene products (alpha-lactalbumin, CEA, casein, fatty acid synthetase, thymidine kinase) have been developed and we are studying the effects of steroid hormones, insulin and prolactin on the activities and synthesis of these proteins. C. We are investigating glucocorticoid receptors in various subpopulations of normal and leukemic lymphoid cells, including their regulation by mitogens such as phytohemaglutinin. In addition we are studying glucocorticoid receptors in Burkitts Lymphoma, hairy cell leukemia, ANLL and lymphomas. D. We have developed a prolactin responsive rat mammary cancer cell line in tissue culture. This is the first in vitro long term prolactin dependent system to be characterized and as such, appears particularly promising for the study of the mechanism of prolactin action. E. We are characterizing an activity derived from bovine mammary gland which appears to be inhibitory of but not lethal to breast epithelial cells in culture and as such may qualify as a putative chalone. BIBLIOGRAPHIC REFERENCES: Thompson, E.B., Aviv, D., and Lippman, M.E.: Variants of HTC Cells with Low Tyrosine Aminotransferinase Inducibility and Apparently Normal Glucocorticoid Receptors. Endocrinology 100: 406-419, 1977. Aitken, S. and Lippman, M.E.: A Simple Computer Program for Quantification and Scatchard Analysis of Steroid Receptor Proteins. J. Steroid Biochemistry 8: 77-94, 1977.